package com.neuedu.wemall.common.util;


import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;
import java.math.BigInteger;
import java.security.SecureRandom;
import java.util.Base64;

public class AESUtils {
    public static boolean isEmpty(String s) {
        if (s == null || s.length() == 0) {
            return true;
        }
        return false;
    }

    /**
     * 将byte[]转为各种进制的字符串
     *
     * @param bytes byte[]
     * @param radix 可以转换进制的范围，从Character.MIN_RADIX到Character.MAX_RADIX，超出范围后变为10进制
     * @return 转换后的字符串
     */
    public static String binary(byte[] bytes, int radix) {
        return new BigInteger(1, bytes).toString(radix);
    }

    /**
     * base 64 encode
     *
     * @param bytes 待编码的byte[]
     * @return 编码后的base 64 code
     */
    public static String base64Encode(byte[] bytes) {
        return Base64.getEncoder().encodeToString(bytes);
    }

    /**
     * base 64 decode
     *
     * @param base64Code 待解码的base 64 code
     * @return 解码后的byte[]
     * @throws Exception
     */
    public static byte[] base64Decode(String base64Code) throws Exception {
        return isEmpty(base64Code) ? null : Base64.getDecoder().decode(base64Code);
    }

    /**
     * AES加密
     *
     * @param content    待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的byte[]
     * @throws Exception
     */
    public static byte[] aesEncryptToBytes(String content, String encryptKey)
            throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128, new SecureRandom(encryptKey.getBytes()));

        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(kgen.generateKey()
                .getEncoded(), "AES"));
        return cipher.doFinal(content.getBytes("utf-8"));
    }

    /**
     * AES加密为base 64 code
     *
     * @param content    待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的base 64 code
     * @throws Exception
     */
    public static String aesEncrypt(String content, String encryptKey) {
        try {
            return base64Encode(aesEncryptToBytes(content, encryptKey));
        } catch (Exception e) {
            throw  new RuntimeException(e);
        }
    }

    /**
     * AES解密
     *
     * @param encryptBytes 待解密的byte[]
     * @param decryptKey   解密密钥
     * @return 解密后的String
     * @throws Exception
     */
    public static String aesDecryptByBytes(byte[] encryptBytes,
                                           String decryptKey) throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128, new SecureRandom(decryptKey.getBytes()));

        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(kgen.generateKey()
                .getEncoded(), "AES"));
        byte[] decryptBytes = cipher.doFinal(encryptBytes);

        return new String(decryptBytes, "UTF-8");
    }

    /**
     * 将base 64 code AES解密
     *
     * @param encryptStr 待解密的base 64 code
     * @param
     * @return 解密后的string
     * @throws Exception
     */
    public static String aesDecrypt(String encryptStr, String decryptKey)
            throws Exception {
        return isEmpty(encryptStr) ? null : aesDecryptByBytes(
                base64Decode(encryptStr), decryptKey);
    }

}
